Graphene oxide grafted with 1,4-piperazinediethylamine for the effective inhibition of the corrosion of X60 carbon steel in CO₂-saturated NaCl environment

CO₂ corrosion is one of the most common and vicious types of corrosion in the gas and oil industry. The most common technique for reducing oil and gas pipelines’ CO₂ corrosion is the employment of corrosion inhibitors. The efficacy of 1,4-piperazinediethylamine functionalization (PD-GO) as an inhibitor against the corrosion of X60 carbon steel in a deoxygenated 3.5 wt% NaCl solution saturated with CO₂ under static and hydrodynamic flow systems was evaluated. A mixture of electrochemical and surface characterization techniques was used to evaluate the performance of the inhibitor. PD-GO demonstrated an excellent inhibition efficacy of over 90% at a concentration of as low as 4 ppm. The presence of the inhibitor improves the carbon steel’s ability to resist charge transfer. Under static conditions, PD-GO behaved more like an anodic-type inhibitor while as a cathodic-type inhibitor under hydrodynamic conditions. Adsorption of PD-GO molecules onto the steel substrate follows the Langmuir isotherm theory, indicating a mix of physical and chemical adsorption mechanisms. An evaluation of the steel substrate’s surface using SEM, AFM, and XPS confirmed the inhibitor’s adsorption to the steel surface to provide the protective film that blocks the corrosive species from reaching the steel surface.